People often have multiple telecommunication devices such as cellular phones, tablet computers, laptops, and other devices. Each device may have its own communication address, such as an email address or telephone number. When calling or sending a message to a desired recipient, the email address or telephone number may be used to specify the recipient.
In the case of email, a person may have several devices configured to send and receive messages using a particular account and a corresponding email address. In the case of traditional carrier-supported messaging services such as SMS (short message service) or MMS (multimedia message service), however, message recipients are usually designated by telephone numbers, each of which is associated with only a single device.